Castration-resistant prostate cancers (CRPC) are one of the challenges in oncology practice. Although there have been advances in chemotherapy10, new hormonal agents11, and immunotherapeutics12, patients in this subgroup still have limited life expectancy. Therefore, there is an urgent need to identify therapeutic targets and clinical development of target agents for the treatment of CRPC. For this end, sorafenib has been tested in multiple phase II studies earlier13-17; however, the clinical efficacy was very limited. The low efficacy of sorafenib might be partly explained by the lower potency in inhibition of RTKs. Considering nanomolar concentration range of IC50 for TKI258 compared with micromolar concentration for other multi-TKIs, the efficacy of TKI258 should be evaluated in CRPC patients.